Decelerator for catapult pistons



priH 4, E950 J. E. sci-101.1. v l 2,50247 DECELERATQR FOR CATAPULT PIs'ToNs Filed March 14, 1946 u ag 'NS s u.

"ab Js JAMES E SOHOLL Patented Apr. 4, 1950 vUNITED `STATES PATENT GFFICE DECELERATOR Fon cA'rAPUL'r PIs'roNs James Edward Scholl, Washington, D. C.

Application March 14, 1946, Serial No. 654,482

(01.121-38) (Granted under the act of March 3, 1883, as

1 Claim.

amended April 30, 1928; l370 0. G. '757) This invention is directed to a decelerator for a catapult piston and particularly for use in a slotted type of catapult or projecting cylinder.

In the slotted type of catapult or projector cylinder, a lluid is used to propel a piston. The piston is provided with a lug which extends through the cylinder slot and engages the vehicle or object to be propelled. It has been the practice in catapulting a plane from the deck of a ship to have the piston lug engage a carriage which in turn supports the plane. The piston and carriage are propelled at a high rate of speed to build up flying speed for the plane by the time the carriage reaches the end of its run within the cylinder. The piston lug and carriage at great expense are projected from the end of the cylinder and are lost.

The object of this invention is to provide a braking system for decelerating the piston, lug and carriage so that they can be reclaimed and Details of the invention are described in connection with the following drawing in which Figure 1 is a plan view of the end portion of the cylinder tube.

Figure 2 is a longitudinal section view of al means of fluid pressure from a suitable source behind the piston. Lug 5 is carried by piston 4 in any suitable manner and extends through slot 2 in cylinder I to engage the carriage or object to be propelled (not shown) Sincev it is desirable to build up enormous pressures of the order of 5,000 pounds/sq. inch behind the piston, a proper seal becomes necessary for slot 2 in order to close the cylinder against possible loss in pressure. In the preferred form of the invention as shown, a sealing strip 6 of any desired flexible material is engaged by guide slot 'l in piston 4 and is carried into sealing engagement as the piston is propelled in the tube. Once in position, fluid pressure behind the piston retains the sealing strip in sealing engagement. It will be apparent that other types of sealing means may be used Without departing from the scope of this invention. Several of these sealing strips are shown in applicants prior application No. 592,156 led May 5, 1945, now abandoned.

To decelerate and stop the piston 4 before it reaches the cylinder closure member 3, pressure is built up in the portion of cylinder I ahead of the piston. This is done by providing diverting tubes 8 which extend between diverting ports 9 and bypass a portion of the propulsive iluid from behind the piston to the ports ahead of the piston as the rear `face of the piston passes the rear set of ports. As the piston reaches a position covering the forward ports, the uid ahead of the piston is compressed to increasingly higher pressure. The work performed during this compression causes the piston to stop. Exhaust ports I0 may be used to open the slotted cylinder behind the piston to the atmosphere thereby decreasing the pressure of the propulsive iuid and increasing the work available to stop the piston.

In addition to using the exhaust ports to decrease the pressure behind the piston, it is desirable to control the rate of deceleration of the piston within certain limits to avoid building up a pressure in iront of the piston that could be great enough to explode the cylinder. This is accomplished by providing an exhaust outlet I8 at the end of the cylinder together with pressure limiting valve II in such outlet I8. This valve II will be so adjusted that it will permit the decelerating pressure in the cylinder to build up to the set safe limit, and that any pressure above that limit will be bled oi by the exhaust outlet I8.

In order to seal the slotted cylinder ahead of the piston during the braking or decelerating stroke, the same sealing strip used to seal the cylinder behind the piston may be used as shown in Figures 1-3 inclusive wherein the diverted uid acts to maintain the sealing strip in sealing engagement. By sealing the cylinder in this manner and injecting iiuid under pressure, it is possible to salvage the piston after each launching.

Stiffeners Il are used 4'at desired intervals to reinforce the slotted tube to withstand pressure from within. Although the means for returning the piston to its starting position form no part of this invention, it may be returned in any of several ways, such as by attaching a cable to the lug 5, or by wrapping patch closures about the exhaust ports I0 and providing low pressure to move the piston after also providing one way valves in the diverting tubes.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes Without the payment of any royalties thereon or therefor.

What is' claimed is:

In a catapult projecting device wherein a pist0n is slidably propelled by uid pressure through a cylinder; means for decelerating the piston as it approaches the end of the cylinder comprising a pressure limiting .exhaust valve at .such end of the cylinder, means adjacent such end of the cylinder for diverting a portion of the propelling fluid pressure from behind the piston to in from' of the piston to provide a decelerating pressure, and means for thereafter :exhausting the remainder of the propelling fluid pressure from behind the piston, said pressure diverting `means comprising ya tube connected toY the, cylinder by ports therein spaced apart a distance greater than the length of the piston, said remainder fluid pressure exhausting means comprising exhaust port means located in the. cylinder ,ntermediate said diverting tube ports, the distance between said exhaust port means vand each of said tube .ports being less than the length of the piston, whereby .the piston will close said exhaust port means before it opens `the, first diverting tube port, and will maintain such exhaust port means in closed condition until the piston has closed ol the second diverting tube port to trap fluid pressure ahead of the piston and then open said exhaust port means to exhaust the pressure still behind the piston.

JAMES EDWARD SCHOLL.

i REFERENCES CITED The following references are of record in the le of` this patent:

UNITED STATES PATENTS Number Name Date 855,266 Thorschmidt May 28, 1907 1,807,231 Weeks May 26, 1931 1,897,350 Wiegner Feb. 14, 1933 1,966,608 Cardwell July 17, 1934 2,038,595 Noble Apr. 28, 1936 2,045,945 Carr June 20,1936 2,109,128 Carrillo Feb. 22, 1938 2,200,427' Merz May 14, `1940 2,403,328 Banning July 2, 1946 

